Of high concern, they write, “is Sen. Hagel’s outlook toward Iran – a country that, among other acts of war against our country, employed its proxy, Hezbollah, to bomb the Marine barracks in Beirut in 1983, resulting in the deaths 241 American servicemen.”

“Sen. Hagel has repeatedly refused to support sanctions against Iran while in the Senate, and in 2006, he stated that ‘a military strike against Iran, a military option, is not a viable, feasible, responsible option,’” the former military leaders write.

“This ill-advised statement telegraphs to Tehran that it should not fear a U.S. military response to the continued pursuit of Iranian nuclear weapons. Whichever policies are pursued with the objective of preventing a nuclear Iran can only have hope of success if backed by a credible military deterrent. It would be unwise to confirm a nominee for Secretary of Defense who has already publicly taken that option off the table,” they say.

“It is our professional assessment that confirmation of Sen. Hagel to be Secretary of Defense would be contrary to the United States’ vital national security interests.”

The letter comes just as Washington is set to consider whether Hagel is qualified for the job.

It is addressed to Sen. Carl Levin, D-Mich., the chairman of the Senate Armed Services Committee, and Sen. James Inhofe, R-Okla., ranking GOP member of the committee.

In the letter, found on the Center for Security Policy’s website, the military leaders cite four reasons for opposing Hagel’s confirmation.

In addition to his problematic attitude toward Iran, they write about Hagel’s eagerness to cut the military budget, which is “at odds with the judgment of the Pentagon’s current civilian and military leadership.”

Further military spending cuts would have “dire effects … on our defense capabilities.”

And they oppose his support for the “Global Zero” plan, a transnational effort to reduce and eliminate nuclear weapons.

When Russia and China are upgrading their nukes, North Korea “is enhancing its long-range nuclear delivery systems and the weapons they will carry and Iran is moving ever closer to obtaining such arms, we cannot responsibly abandon our deterrent,” they say.

They also say Hagel’s “hostility toward Israel” is out of place, specifically citing as an example his refusal to “sign a letter expressing support for Israel during the second Palestinian intifada.”

He was one of only three senators who refused.

The signatories to the letter are:

Adm. James “Ace” Lyons, USN (Ret.)

Lt. Gen. William G. “Jerry” Boykin, USA (Ret.)

Vice Adm. Robert Monroe, USN (Ret.)

Lt. Gen. E.G. “Buck” Shuler, Jr., USAF (Ret.)

Maj. Gen. Thomas F. Cole, USA (Ret.)

Maj. Gen. Vincent E. Falter, USA (Ret.)

Rear Adm. H.E. Gerhard, USN (Ret.)

Rear Adm. Robert H. Gormley, USN (Ret.)

Maj. Gen. Geoffrey Higginbotham, USMC (Ret.)

Rear Adm. Don G. Primeau, USN (Ret.)

Maj. Gen. Mel Thrash, USA (Ret.)

Maj. Gen. Paul E. Vallely, USA (Ret.)

Brig. Gen. William A. Bloomer, USMC (Ret.)

Brig. Gen. Ronald K. Kerwood, USA (Ret.)

The letter was facilitated by Frank J. Gaffney Jr., president of the Center for Security Policy.

“These military leaders deserve our profound thanks,” Gaffney said, “for once again acting in service to our nation – in this instance, for the purpose of raising awareness of the risks associated with confirming Sen. Chuck Hagel to be secretary of defense.”

He said Hagel “lacks these qualities, and hopefully the United States Senate will heed the concerns of these flag and general officers during the course of his confirmation process.”